Acoustic diaphragm



'May 24, 1932. R Y 1,859,782

ACOUSTI C DIAPHRAGM Filed June 11, 1929 INVENTOR RUsSELL P. Y BY ATTORNEY Patented May 24, 1932 UNITED STATES PATENT OFFICE RUSSELL IP. MAY, OF NEW YORK, N. Y., ASSIGNOR TO RADIO CORPORATION OF AMERICA,

A CORPORATION OF DELAWARE ACOUSTIC DIAPHRAGM Application filed June .11, 1929. Serial No. 369,977.

This invention relates to a diaphragm for acoustic devices. More particularly this invention relates to a metallic diaphragm of the type which is clamped around its periphery and is provided adjacent its periphery with a flexible portion.

.The object of this invention is to provide an improveddiaphragm which has a relatively rigid central portion, an annular mounting rim and a flexible portion between the rigid portion and the mounting rim 4 Another object of the invention is to provide a diaphragm of the type described which is cheaply and easily manufactured by a die stamping process. g Other objects of my invention will become apparent on reading the following specification in connection with the accompanying v drawings, in which Figure 1 illustrates a plan View of a diaphragm made in accordance with my invention, and

Figure 2 is a sectional View of Figure 1.

Referringmore particularly to the drawings, the diaphragm is formed from a fiat piece of suitable material such as sheet metal, in a manner such that it has a relatively rigid central portion 10, a substantially flexible annular portion 11 surrounding the rigid portion 10 and an annular mounting rim 12 surrounding the flex'ible'portion 11. The central portion-is preferably provided with concentric corrugations for the purpose of adding rigidity to this portion. The corrugations are obtained by die stamping and in the preferred embodiment of my invention the corrugations form V shaped grooves. Other types of corrugation, however, may be used for adding rigidity to the central portion of the diaphragm without departing from the spirit of the invention.

The flexible portion of the diaphragm is also formed by die stamping V shaped grooves into the diaphragm material. But in this case the grooves are stamped eecentrically to the first mentioned grooves and only in the annular portion surrounding the rigid central portion. If the centers of the eccentric grooves are located on a circle concentric with the first mentioned grooves and if they are spaced at equal intervals around this circle, the eccentric grooves will form a plurality of small diamond shaped projections in the said annular portion of the diaphragm. As shown in Figure 1 the series of projections 1, 2, 3 and 4 lie on an eccentric groove which is an arc of a circle whose center is at point A on circle D and whose radius is the distance 1A. The next inner series of projections 5, 6, 7 and 8 lie on an eccentric groove also an arc of a circle whose center is at point B on circle D and whose radius 5-B is equal to the radiusl- A. The eccentric groove forming the next inner series of projections is a circular arc whose center is at point C. By spacing the points A, B, C etc. at equal distances apart on circle D, the diamond shaped projections described are formed. Thus while the eccentric grooves may be circular in shape, the two sides of any groove make an angle with each other which I refer to. as V-shaped. This arrangement makes a very flexible portion and as it only requires a few die stampings the resultant diaphragm is easily and cheaply manufactured.

The annular mounting rim is left unstamped. This rim is secured between the supporting or diaphragm clamping portions of the acoustic device.

The annular suspension portion may also be formed by stamping a plurality of spiral grooves about the center of the diaphragm. In such a case the spiral grooves do not extend into the rigid portion of the diaphragm but are only stamped in the annular portion surrounding the rigid central portion.

It is to be understood that I have illustrated and described only a preferred form of my invention and that various modifications and variations can be made without departing from the spirit of the invention. Accordingly I do not desire to be limited by the specific modification illustrated but only by the scope of the appended claims.

In the appended claims the term stamping is used to indicate distorting out of the plane of the original suiface.

I claim:

1. A diaphragm comprising a circular metallic sheet provided with central concentric circular stampings and eccentric circular stampings surrounding said central concentric stampings. 5 2. A diaphragm comprising a circular metallic sheet provided with central concentric stam ings, eccentric circular stampings surroun 'ng said central concentric stampings, and an annular unstamped portion surrounding the eccentrically stamped portion.

3. A diaphragm comprising a sheet of suitable material rovided with a plurality of stampings for orming a relatively ri id central portion and a second pluralit 0 stampin s for forming a relatively flexi le portion,

said second plurality of stampings consisting of a plurality of intersecting, equal diameter, circular grooves.

' 4. The method of forming a flexible portion in a die hragm which consists in stamping the diap ragm with a plurality of intersecting eccentric grooves.

5. The method of forming a diaphragm which consists in stamping one portion of the diaphragm with a plurality of concentric circular grooves and stamping a second portion of the diaphragm with a plurality of intersecting circular grooves eccentric to said concentric grooves.

6. The method of forming a diaphragm which consists in stamping a central portion of the diaphragm with a plurality of concentric V shaped grooves and in stamping an annular portion of the diaphragm with a plurality of intersecting eccentric V shaped grooves.

7. The method of forming a flexible portion in a diaphragm which consists in stampping a plurality of intersectingcircular grooves eccentrically around the center of said diaphragm.

8. The method of forming a flexible portion in a diaphragm which consists in stamping a plurality of intersecting circular grooves eccentrically around the center of said diaphragm, each of said grooves being of the same radius as the other grooves.

RUSSELL P. MAY.

CERTIFICATE or GORllEGTlON.

Patent No. 1,859,782. May 24, 1932. f

7 RUSSELL 1*; MAY;

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 1, line 81, beginning with the word "The" strike out all to and including the word "portion. in line 87, and insert instead- The diaphragm may be used as the diaphragm ofan ordinary telephone receiver or it may be actuated from a stylus vibrated by a I phonograph record. In the former case it is only necessary to form the diaphragm from magnetic material and to place it in a magnetic. field in the well known manner. In the latter case a spider member 13 is preferably connected at several points to one of the ridges formed by the' concentric V shaeed grooves, and a suitable-member 14 is provided for connecting the spider 13 with the stylus. v The diaphragm'may also be dynamically driven. In such a the diaphragm which need'notbe of magnetic material is provided within suitable driving coil in any well known manner.; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record ofthe case in the Patent Office. p

Signed andsealed this 1st day of November; A. D. 1%2. A

M. J. Moore, Acting Commissioner of Patents.

(Seal) I 

